Biometrics is the use of distinctive biological and/or behavioral characteristics to identify an individual. Archeological evidence shows that the history of biometrics dates as early as 6,000 B.C., when human fingerprints were used to associate a person with an event or a transaction. The first modern wide-spread use of biometrics was the capture of hand images for use in identification, developed in 1858 by Sir William Herschel. Since then, biometric technology progressed quickly, and widespread use of fingerprint identification led to the development of automated fingerprint scanning and identifying systems. Presently, fingerprint identification is still the most common form of biometric identification used in the world. But many high security institutions such as the FBI, CIA, and NASA have recently employed iris scanning. Other biometric technologies that exist utilize speech, face, signature, and palm recognition.
Although fingerprint biometrics has proven effective, its public perception is weak, collection of high quality prints is difficult, and age and occupation can alter person's fingerprints. Moreover, images of fingerprints can also be fabricated and used to spoof security systems. Face recognition was thought to be a good means of identification, but facial recognition is sensitive to changes in light and expression, people's faces change over time, and the current technology in facial recognition produces a lot of false positives. Voice recognition could have been effective because the sensors (e.g., microphones) are easily available, but sensor and channel variances are difficult to control. Recently, iris scanning has been thought to be the best solution because the iris is protected by the cornea and believed to be stable over an individual's lifetime. However, iris scanners are thought to be easily fooled by fake-iris contact lenses.
An idea to use retina vasculature patterns for personnel authentication originated from the work of Dr. Carleton Simon and Dr. Isodore Goldstein, published in the New York State Journal of Medicine in 1935. Every eye, including those of identical twins, has its own unique pattern of blood vessels, allowing for accurate identification. Image acquisition for retina scanning was very impractical and expensive back then; however, today, fundoscopes and other ocular cameras are regularly used by medical professionals to image the retina. In fundoscopy, illumination is flooded onto the retinal surface with (filtered) incandescent or flash light source(s). The illuminated portion of the retina that falls into the field of view of the device is re-imaged by optics onto an image sensor, and then converted into a digital image.